1. Field of the Invention
The present invention relates to a semiconductor light emitting module including e.g. LED chips for emitting red light, green light and blue light. The invention also relates to an image reader using such a semiconductor light emitting module.
2. Description of the Related Art
FIG. 8 shows a conventional semiconductor light emitting module (see JP-A-2007-78916). The illustrated semiconductor light emitting module X includes a lead 91, three LED chips 92 and a resin package 93. The lead 91 is utilized for supplying power to the LED chips 92 and includes a die bonding pad 91a, a wire bonding pad 91b and terminals 91c. The die bonding pad 91a comprises three lands. The LED chips 92 are bonded to the lands, respectively. The three LED chips 92 emit red light, green light and blue light, respectively. Each of the LED chips 92 is connected to the wire bonding pad 91b via a wire. The terminals 91c are utilized for connecting the semiconductor light emitting module X to a circuit board for mounting to an image reader, for example. The resin package 93 is made of e.g. white resin and partially covers the lead 91. The resin package 93 is formed with an opening 93a. The opening 93a exposes the three LED chips 92.
When the semiconductor light emitting module X is used for an image reader, a light guiding member is arranged to face the semiconductor light emitting module X. The light guiding member is in the form of an elongated bar and is so arranged that one of its end surfaces faces the LED chips 92. The light enters the light guiding member through the end surface and is reflected in the width direction while traveling in the longitudinal direction. Thus, from the light guiding member, linear light extending in the longitudinal direction is emitted. The linear light illuminates the object to be read such as a document. The light reflected by the object is received by e.g. sensor IC chips, whereby the content of the document is read as image data.
To obtain proper image data, it is necessary to illuminate the document uniformly with linear light having a high intensity. To achieve this, it may be sometimes necessary to change the arrangement of the LED chips 92. However, when the arrangement of the LED chips 92 is changed, the shape and arrangement of the die bonding pad 91a also need to be changed. This causes an increase in the cost for manufacturing the semiconductor light emitting module and the image reader.